Phonograph-needle



M. L STRAIGHT.

PHONOGRAPH NEEDLE.

APPLICATION FILED M'AR. 3|, 1919.

1,8 98,529. Patented. Nov. 29, 1921'.

- UNITED STATES MERTON STRAIGHT, OF ABEL, IOWA.

PHONOGRAPH-NEEDLE.

Specification of Letters Patent.

Patented Nov. 29, 1921.

Application filed March 81, 15 19. SeriaI Ho. 286,534.

To all whom it may concern:

Be it known that I, MERTON T. STRAIGHT,

' a citizen of the United States, residing at ones.

Adel, in the county of Dallas, State of Iowa, have invented .aPhonograph-Needle, of which the followin is the specification.

My invention re ates to styli for gramophones and particularly to thosestyli whlch are adapted to be used in, talking machines to reproducesound from commerclal sound record tablets. When a steel stylus is bemgused to reproduce sound from a sound rec'- ord tablet, the tip orpointof the stylus always wears to a perceptible extent and a sharp edgeis formed thereon wh1ch tends to cut and unduly wear away the walls ofthe grooves of the tablets and to produce a scratching sound. Thiswearing away of the stylus point has a tendency to embed small particlesof steel in the walls of the.

grooves and thereby increase the scratching noises and theseembeddedparticles in turn tend to increase the wear on the points of thestyli. On account of the excessive wear of the stylus point and the wearon the sides of the grooves of the sound reproducing tablet, it iscustomary to use the steel stylus but once and when it has sobeen'used,'throw it away and replace it with a new one. The necessity ofhaving to change the stylus every time a record tablet is played, isannoying to say nothing of the liability of getting the used styli mixedwith the unused Styli'formed of a material softer than steel, such astungsten, 'do not wear the sides of the sound grooves as much as steelstyli do, but have a tendency to wear blunt and'thereby fillthe smallangular notches in the grooves with the material worn from the styli. Onaccount of the small notches being partly filled and the blunt portionsof the styli having a tendency to ride over the smaller notches, some ofthe details of the tones'are sacrificed.

Therefore the object of my invention is to obviate the necessity ofchanging styli for each reproduction of sound from a record tabletand'to produce a stylus of cheap ma- .terial and one that iscomparativel inexpensive to manufacture WhlCh may, e used to reproducesound from a large number of tablets without substantlal 1n ury to thetablets and also toeliminate the scratching noise without sacrifice tothe quality of tone.

A further object is to provide in connection with a stylus formed ofnatural clays or shales, new and improved means for clamping the stylusin the sound head of the sound producing machine.

Referring to the accompanying drawings:

Figure 1 shows a side elevation of the sound reproducing record and thesound head with one of my improved styli in position.

Fig. 2 shows a side elevation of the stylus.

Fig. 3 is a detailed end view of the stylus supporting member showingthe stylus in section.

Fig. 4 shows a perspective view ofmy improved stylus supporting clamp.

Fig. 5 shows the top elevation of one of the trays in which the styliareplaced while being burned. r

' Fig. 6 shows a sectional perspective 'view of the trays in positionrelative to each other and taken on the line 6-6 of Fig. 5.

I have discovered that certain kinds of natural shale and clay possessthe proper ingredients to make excellent styli for sound reproducingmachines, capable of transmitting sound waves to the diaphragm in such amanner as to produce a mellow tone of fine quality and at the same timehave a very hard and smooth surface which does not wear when engagingthe grooves of a sound reproducing record.

In producing the styli, I first select material possessing the properingredients, preferably a red shale. This shale has a very fine grainand no rough particles and a large amount of aluminates and oxid ofiron. In its natural state it possesses the property of being easilycutto'any desired shape and doesnot have to be ground or mixed beforebeing burned or vitrified.

In making my styli I preferably cut the natural shale insquare barswhich are dried at normal temperatures to harden and the bars of shaleare dried they are placed in a special machine and cut to a cylindricalform having a taperin point at one end illustrated in Fig. 2 o thedrawings and designated by the numeral 10. Sometimes it may be desirableto polish the point before being burned. This may be done by a specialbufling wheel. The nature of the shale 5 from which the stylus is madesomewhat determines this part of the process. The styli are now ready tobe burned. To accomplish this without overheating and burningthe finepoints and to prevent bending and warping them, I have provided a tray11 having a top tray member 12 clearly illustrated in Figs. 5 and 6 ofthe drawings. The trays may be made of porcelain or any 7 suitable fireproof material. The tray 11 has in its upper surface a series of grooves13 substantially the size and shape of a stylus and of a depth equal toone-half of the diameter of the stylus. A flange 14 .is provided on theouter edge of the upper face of the tray 11 and is designed to form aretaining rib. The top tray 12 has its under side portion provided withgrooves 15 similar to those in the tray 12 and so spaced as to alinewith the grooves 13, of the tray 11. When in position thereon, the tray12 is held in position by the ribs 14 so that the grooves 15 willproperly align with the grooves 13. When each of the grooves 13 has beenfilled with unburned styli, I place the top tray 12 in position andplace the said trays in a suitable furnace or kiln. Heat is then appliedand the temperature is gradually raised to a point where the styli willvitrify, after which the temperature is gradually lowered to normal. Thestyli are then removed from the trays and are ready for use.

I have found that styli so produced have the hardness about equal tothat of a sapphire and have a very close-grained, smooth and polishedsurface.

I have found, however, that styli so made are somewhat brittle and havea tendency to breakwhen clamped in position in the sound head. This isdue to the fact that the pressure applied by the set screw is unequallydistributed over the surface of the stylus. To overcome this diflicultyI have provided a pressure plate 16.

Fig. 1 shows a. gramophone body 17 hav ing a record 18, a sound head 19,the said head being provided with a stylus supporting member 20, all ofwhich are of the ordinary construction and form no part of thisinvention.

The stylus supporting members are generally provided with a triangularshaped opening 21. The pressure plate 16 is designed to be made of softsteel or similar material and is of such a size as to loosely fit thelarge part of the opening 21 and has two parallel faces 22 and 23, andtwo inwardly inclined faces 25. One of the parallel faces is providedwith a longitudinal cirs b cular groove 26, and is of a length equal toor longer than the opening 21. When it is desired to place a stylus inthe opening 21 of the sound head, the cylindrical portion of the stylus10 is placed in the opening 21, and adjacent to the angle opposlte theset screw 24. The plate 16 isthen slid in the opening with the face 22adjacent to the side having the set screw, with the groove 26 adjacentto the stylus. If the set screw 24 is now turned, it will be seen thatthe stylus will be firmly gripped and the pressure evenly distributed,without breaking the stylus.

I have thus produced a stylus adapted to be used in connection with agramophone or other sound reproducing mechanism that does not have to bechanged when a new record is placed and can be used a very large numberof times without injury to the sound reproducing record and at the sametime eliminates the excessive noises without sacrificing the quality andclearness of the tone.

I am aware that heretofore a large variety of materials have beenemployed in the manufacture of styli for sound reproducing machines-andthat numerous patents have been granted .for the discovery of thesevarious substances or materials as designed for use in sound reproducingmachines. At the present time, however, only two general classes ofthese materials have remained in general commercial use, and these twoare steel and jewels.

The objections to the use of steel for this purpose have been heretoforeset forth.

The objection to the use of jewels for this purpose is, primarily, inregard to their practically prohibitive expense.

The merit of'my invention or discovery. resides primarily in providing astylus by which the same, or better, results, acoustically speaking, maybe obtained as are obtained by the use of jewels, and at the same timeprovide such stylus at a cost which is merely nominal as compared withthe cost of jewels, thus resulting in a great sav1ng of expense to theusers of sound reproducing machines and at the same time gaining all ofthe advantageous results, both acoustically and mechanically speaking,as are attained by the use of jewels, and avoiding the difiiculties anddisadvantages, both acoustic and mechanical, that are inherent in thecheaper materials that have heretofore been used for this purpose, suchasthe necessity of frequently changing the styli, the injury to therecords by the deposit of particles worn from the styli, and thedefective acoustic properties thereof.

Another marked advantage of my invention is that necessary shaping andpolishing may be done upon the natural shale before it is vitrified, andthis obviously can be done much more rapidly, efliciently andeconomically than could be done after vitrification.

Furthermore in this connection, where the shaping of the stylus is donebefore it is hardened, then during the process of vitrification theexterior of the stylus becomes smooth, hard and tough, and far betterfor the purposes intended than if the shaping and polishing were doneafter hardening or vitrification.

I claim:

1. A stylus for sound reproducing ma- 10- chines, formed of naturalshale artificially vitrified. 2. A stylus point machine's, formed ofnatural shale polished and artificially vitrified.

MERTON T. STRAIGHT.

for sound reproducing I

